Research group Werner

Tomáš Werner has moved to the University of Graz, where he has been appointed as university professor and head of the research group Molecular Plant Physiology. Informations about his group there can be found on the pages of the research group Molecular Plant Physiology.

Parts of the group still reside here in Berlin.

Research interest

Plant development and growth are multifactorial processes regulated by a large number of endogenous signals and environmental cues. Besides other functions, the plant hormone cytokinin is a key morphogenic factor controlling cell division and thus formation and growth rate of organs during the plant life cycle. The question, which plant developmental programs are under cytokinin control and which molecular mechanisms underlie cytokinin action in these processes, is in the focus of our research.

Schematic model of cytokinin metabolism. Biosynthesis of cytokinins is initiated by adenosine phosphate-isopentenyltransferases (IPTs) to form iP-nucleotides which can be converted to the corresponding tZ-nucleotides by cytochrome P450 monooxygenases (CYP735As). Cytokinin nucleotides can be directly converted to active free bases by cytokinin nucleoside 5'-monophosphate phosphoribohydrolases (LOGs). Biologically active cytokinins are highlighted in grey, and can be inactivated by cytokinin oxidases/dehydrogenases (CKXs) and by conjugation to sugar moieties through glycosyltransferases (UGTs).

We are interested in metabolic regulation of cytokinin concentration in plant cell with a specific focus on catabolic pathway mediated by cytokinin oxidases/dehydrogenases (CKX) enzymes.
We also aim to understand underlying mechanisms of cytokinin activity and to identify new genetic factors, which mediate or interact with the hormone activity. To this end, we carried out a suppressor mutagenesis of cytokinin deficient Arabidopsis plants - plants overexpressing CKX gene and displaying complex phenotypic changes such as dwarfed shoot - and screened for a phenotypic reversion. We isolated several recessive and dominant second-site suppressor alleles termed rock (repressor of cytokinin deficiency), which we currently map and functionally characterise.

Examples of phenotypic reversions in different second-site rock suppressor lines.